Minimum Range for OBA

[Eagle4ty]

I would think something like 20 hexes would fit the bill for ASL as an abstraction as much as ASL in itself is an abstraction. For instance APDS was never to be fired over the heads of friendly troops not in prepared positions as a matter of standard practice because of the discarding portion of the projectile (same for canister BTW). "Danger Close" to friendly troops for much artillery fire (OBA) ranged from 400-600m or about 10 to 15 hexes away from friendlies and by standard practice should probably include another TC DR to be used closer than that. If you would want to dive into the exact angle of deflection allowed by a gun system and figure out its minimum standard range based upon that and charge component available/used I guess it would lend a degree of accuracy to the scenario design but there's probably a point of diminishing returns.

 

[Actionjick]

I would think something like 20 hexes would fit the bill for ASL as an abstraction as much as ASL in itself is an abstraction. For instance APDS was never to be fired over the heads of friendly troops not in prepared positions as a matter of standard practice because of the discarding portion of the projectile (same for canister BTW). "Danger Close" to friendly troops for much artillery fire (OBA) ranged from 400-600m or about 10 to 15 hexes away from friendlies and by standard practice should probably include another TC DR to be used closer than that. If you would want to dive into the exact angle of deflection allowed by a gun system and figure out its minimum standard range based upon that and charge component available/used I guess it would lend a degree of accuracy to the scenario design but there's probably a point of diminishing returns.

Nice information!

 

[KhandidGamera]

The terrain is Korea and the battery is in the valley and the bad guys are coming for them from behind a big hill. The good guys are trying to stop the guys from coming over the hill, the good guys are trying to keep the direct fire fight from the guns.

However, after writing two different SSRs for it, I think there is a simpler way to have the similar effect.

But as stated above, 20 hexes away is probably correct so it wouldn't work in this scenario to allow the guns in the valley to do an indirect fire mission on the map.

Thanks for your help.

Haven't been on the board a while, but noticed your thread. As others indicated Jack Daniels would be a great source. Also through Vince (MajorIssues) Jim Thompson would be a very good source too. He had played around with re-working FA for ASL and a professional military knowledge of artillery. Can't but help but get drawn to put my zwei pfennig in as a former 155 mm SP FDO and engineer - like a cat to a laser pointer. Also was in a National Guard artillery battalion that still fielded what the M2A1 became: the M101A1 - ISTR a regular army airborne unit took away their newer M102's.

The thoughts I have are that this seems like a place where High Angle Howitzer fire comes into play - anything greater than 45 degrees AND zeroing in how to set time fuzes if VT fuzes weren't available. From the brief scan I did for period time fuzes, you had to adjust in to find what the right time setting would be for the best high angle quadrant/charge combination to burst over the bad guys just behind the crest of the hill and be safe/have fast time of flight. It seems like 10-20 hexes might be right - I always remember 400 meters as danger close. This is also of course just a classic projectile motion problem - which is relevant if you don't have tables for high angle charge-quadrant-range tables, but also to figure out when the round reaches above the enemy coming down, when your shooting from the valley below and enemy is above at a different elevation. The difference in elevations and high angle make the question more complicated. If you have muzzle velocity for the charge used then that's better then nothing and the projectile equations work - it just won't take in met (weather/wind) In late 80's we had stick log scales to back up our BCS and would imagine that's what would be around in Korea. Curious as to how high the ridge is from the valley and how far away. I'm saying more here than less as I don't know what mortars do/don't do compared to FA. Looking at the ammunition there's seven zones of charge for M2A1 - don't know if that means 7 charge possibilities and seven sets of quadrant/curves, but it seems like a lot of adjustment available. A battery would be 4-6 guns, and the M2A1 per wiki deflect about 23 degrees each way if I'm assuming right the 46 degrees is total. What the sheaf possibilities would be like = how close guns were to each other.

Poking around I found this rather topical Aberdeen doc that can be downloaded - also covers 76mm and 90mm guns, there's also one for 155mm and up. Note these are July 1950, so right there at Korea with all the background from WW2. Didn't scan thru much in these, but looks very relevant. Writing this post after work, so going to bed now. Kind of intrigued to look and see if there's charge/muzzle velocity numbers to work with and run the problem for say 500m away in the valley to the ridge and a 300m high ridge. If there is actually range-charge-high angle elevation data - super.

 

[Actionjick]

Haven't been on the board a while, but noticed your thread. As others indicated Jack Daniels would be a great source. Also through Vince (MajorIssues) Jim Thompson would be a very good source too. He had played around with re-working FA for ASL and a professional military knowledge of artillery. Can't but help but get drawn to put my zwei pfennig in as a former 155 mm SP FDO and engineer - like a cat to a laser pointer. Also was in a National Guard artillery battalion that still fielded what the M2A1 became: the M101A1 - ISTR a regular army airborne unit took away their newer M102's.

The thoughts I have are that this seems like a place where High Angle Howitzer fire comes into play - anything greater than 45 degrees AND zeroing in how to set time fuzes if VT fuzes weren't available. From the brief scan I did for period time fuzes, you had to adjust in to find what the right time setting would be for the best high angle quadrant/charge combination to burst over the bad guys just behind the crest of the hill and be safe/have fast time of flight. It seems like 10-20 hexes might be right - I always remember 400 meters as danger close. This is also of course just a classic projectile motion problem - which is relevant if you don't have tables for high angle charge-quadrant-range tables, but also to figure out when the round reaches above the enemy coming down, when your shooting from the valley below and enemy is above at a different elevation. The difference in elevations and high angle make the question more complicated. If you have muzzle velocity for the charge used then that's better then nothing and the projectile equations work - it just won't take in met (weather/wind) In late 80's we had stick log scales to back up our BCS and would imagine that's what would be around in Korea. Curious as to how high the ridge is from the valley and how far away. I'm saying more here than less as I don't know what mortars do/don't do compared to FA. Looking at the ammunition there's seven zones of charge for M2A1 - don't know if that means 7 charge possibilities and seven sets of quadrant/curves, but it seems like a lot of adjustment available. A battery would be 4-6 guns, and the M2A1 per wiki deflect about 23 degrees each way if I'm assuming right the 46 degrees is total. What the sheaf possibilities would be like = how close guns were to each other.

Poking around I found this rather topical Aberdeen doc that can be downloaded - also covers 76mm and 90mm guns, there's also one for 155mm and up. Note these are July 1950, so right there at Korea with all the background from WW2. Didn't scan thru much in these, but looks very relevant. Writing this post after work, so going to bed now. Kind of intrigued to look and see if there's charge/muzzle velocity numbers to work with and run the problem for say 500m away in the valley to the ridge and a 300m high ridge. If there is actually range-charge-high angle elevation data - super.

Very nice!